For some years, furniture formed from modular elements has been widely used, including furniture formed by uprights (tubes or bars of square, circular or other cross section) assembled together horizontally and vertically, on which are laid shelves, frontages, doors . . . . These pieces of furniture are very generally sold unassembled in the form of kits and are assembled together by the purchaser. The assembly process and the device for fixing the elements together must then be simple.
As a general rule, the uprights are connected together by means of nodes or jointing pieces which are of two main types: the uprights are fixed by means of a jointing piece in which two or three uprights slide, securing being provided by screwing of a mobile element of the jointing piece. This device has good properties of rigidity of assembly but has the drawback of not being coplanar.
According to another type, assembly takes place by means of elements which fit into the uprights or into which the uprights fit while allowing a coplanar assembly thereof. However, with such systems several tiers of uprights of greater or lesser length cannot be superimposed for they lack rigidity.
Other known devices use jointing pieces to which wood or metal rods are fixed by means of pins.
In most cases, the jointing devices are provided for orientating three uprights in three planes perpendicular to each other but it is generally possible to adapt the jointing pieces to another number of uprights in planes intersecting at angles other than right angles, in particular when it is desired to obtain a frame like structure.